[FFmpeg-devel] ac3 imdct question

Michael Niedermayer michaelni
Mon Oct 13 23:17:20 CEST 2008

On Mon, Oct 13, 2008 at 03:17:53PM +0200, Arpi wrote:
> Hi,
> Could someone DSP guru please explain me, what ff_fft_calc exactly
> calculates in ff_imdct_half_c() of mdct.c ?

it should be doing a IFFT

> I've tried to replace it (for experimenting with pitch correction...)
> with the 'standard' inverse discrete fourier transform but it does
> not work, the sound (ac3 music sample file) gets heavily distorted :(
> here's my modification:

I think your code is buggy ...
see (fft_ref() in) fft-test.c


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
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